Solids cooling means and riser conduit



July 5, 1960A L. s. DANIELS SOLIDS COOLING MEANSv ND RISER CONDUIT FiledApril 1, 1953 United States Patent O SOLIDS'COOLING MEANS AND RISERCONDUIT Ludlow S. Daniels, New York, NX., assignor to HydrocarbonResearch, Inc., New York, N. a corporation of New Jersey Filed Apr. 1,`1953, SenNo.- 346,132

1 Claim. (Cls 23-288) This invention relates. to animproved method andapparatus for carrying out catalytic reactions;

In catalytic reactions involving the circulation of a finely divided.solid contact material orf catalyst between a conversion zone and aregeneration zone, several problems are encountered in transferring thesolids from one zone to the other. 'For instance, the regenerated solidsmustbeV stripped of adsorbed oxygen before enteringI the conversion zoneandthe gasiform reactants in the two zones must be kept from mixingwithl one another; Also, thermal adjustment andcontrol of theregeneratedl solids is required for satisfactoryV operation of theconversion zone.

An object of this invention isto provide improved means for the transferof solids from one zone to another ofa catalytic reaction system.`

A further object is to adjust and control the temperature of the solidsundergoing transfer from one zone to another of thereacticnsystem.

Further. objects and advantages of the invention will be apparent fromthe description which follows.

Briefly, the catalyst or solids transfer means of this inventioncomprises a tubular leg adapted to depend from the bottom of a catalyticreactor, a pneumatic lift conduit extending up through the tubular legwith an annular space between the walls of the leg and conduit andhaving its lower end in communication with the lower end of the leg,anda tube-and-sheet type of heat exchanger dispose'd'in the annularspace through the tubes of' which exchanger' the solids pass beforeentering the open bottom end of the conduit. Steam introduced just belowthe heat exchanger acts in cooperation withrestricted catalystpassageways through the exchanger to strip thecatalyst and seal theupliftV conduit against the leakage of gases from the bottom of thereactor. Operationally, a heat exchange medium circulating around thetubes of the heat exchanger controls the temperature of the catalystpassing through the tubes and may control the rate of flow of catalystthrough the lift conduit. The catalyst transfer unit of this inventionis particularly applicable to reactors through which the catalystcirculates as a moving bed from an upper conversion zone to a contiguouslower regeneration zone and in which the catalyst is entrained in agaseous stream through a lift conduit to transfer catalyst from thebottom of the regeneration zone to the top of the conversion zone.

For a fuller understanding of the invention reference is made to theaccompanying drawing wherein:

Figure 1 is a schematic elevation of a moving bed reactordprovided witha plurality of catalyst transfer units; an

Figure 2 is a schematic sectional elevation of a catalyst transfer unit.

The cylindrical leg 1'2 illustrated in Figure 2 depends substantiallyvertically from a reactor Vessel. Leg 12 contains an annular heatexchanger 14 having two spaced tube sheets 16 and 17 and a plurality ofvertical tubes 18 through which the catalyst flows. Ports 20 and 212,943,922 Patented July 5,- 1960 are used, respectively, to introduceand withdraw aheat exchange medium circulating around tubes 18. Forbrevity, heat exchanger 14 is hereinafter referred to as boiler 14.Beneath boiler 14is an annular plenumrchamber 22 in which the catalystleaving tubes 18 collects. Seal steam introduced through inlet 24justbelow lower tube sheet 17 passes up through tubes 18 incountercurrent stripping contact with the catalyst thereby preventingentry of gases from the reactor into the bottom of leg 12. As shown inFigure 2, the lower ends of tubes 18 preferably project beyond lowertube sheet 17 so that seal steam from inlet 24 ows around the severaltubes 18 in the space left. empty between tube sheet 17 and the catalystmass discharging from tubes 18. Uniform entry of seal steam Vinto tubes18 is thus facilitated. The restricted flow area of tubes 18 simpliliescatalyst stripping and allows eilicient sealing by a small quantity ofsteam.

Beneath the point of seal steam introduction into plenum chamber 22 isanannular steam chest 26 formed by the side wall of leg 12, its bottom28 and frusto-conical skirt 30. Control steam enters through an inlet 34and-exits from chest 26 through the annular space 32 l'left between thelower edge of skirt 30 and bottom 28v of leg 1'2. Frusto-conical. skirt30 is generally disposed at an angle of at least 60 to the horizontal.An inlet 36 entering leg 12 through a suitable connection in bottom 28extends axially past annular space 32 to end just inside conduit 40 inan inwardly flared nozzle 38 while the lower end of leftr conduit 40 hasan outward flaring 42. Lift conduit 40 extends concentrically throughleg 12 and boiler 14 into the reactor vessel. The control steam fromychest 26 flowing through annular space 32 entrains catalyst from thebottom of leg 12, carrying it through the annular opening 44 betweenflaring 42 and nozzle 38 into lift conduit 40 where together with thehuid exiting from inlet 36 it pneumatically transports the catalystupwardly.

Lift conduit 40 is anchored near its bottom by a plurality of radialribs 46 which are bolted to radial ribs 48 projecting towards liftconduit 40 from the walls of leg d2; each radial rib 48 hasV a tab orfoot 50 attached to the bottom 28 of leg 12 for greater structuralstrength. Lift conduit 40 fits loosely in annular boiler 14, with radialguides S2 on the exterior of conduits 40 maintaining concentricity. Uponexpanding or contracting with temperature changes, lift conduit 40 canslide freely up or down without in any way stressing the structure ofboiler 14. The annular space 54 between lift conduit 40 and boiler 14allows some of the catalyst to ow therethrough.

In operation, an increase in the rate of ow of catalyst down throughtubes 18 will increase the rate of heat transfer to the heat exchangemedium in boiler 14. Thus when generating steam in boiler 14, the rateof steam generation provides a convenient indicator of the catalyst Howrate through tubes 13. Accordingly, known means for measuring the rateof steam generation or the rate at which the heat exchange medium picksup heat from the catalyst passing through tubes 18 may be employed inassociation with control means that in response to changes observed bythe measuring means will automatically adjust a valve in line 34. 'Forinstance, a decrease in the desired steam generation noted by themeasuring means would cause the associated control means to open widerlthe valve in line -34 so that more entraining duid would transportcatalyst from plenum chamber 22 into lift conduit 40; thus, the catalystow down through tubes 18 would increase with the result that the rate ofsteam generation would also be increased until the desired rate of steamgeneration was attained. An

'each line 36 is generally desired.

increase in steamA generation beyond the desired rate would act throughthe measuring means and the assov J Inlet line 36 entersV bottom E28 ofleg 12'through a housing 62.v A retainer ring 64, the inner end of whichslides inside-,housing 62, is bolted to housing 62 to compress ilexiblepacking 66 and thus provide a tight seal around line 36. Inlet line 36may be moved vertically to change the size of the annular opening 44.

Figure 1 illustrates a moving bed reactor vessel .v10 provided with amultiplicity of catalyst return legs 12,Y lateral- In view of thevarious modications of the invention which will occur to those skilledin the art upon considly spaced apart from one another in a patternwhereby catalyst discharging from the several lift conduits 49 is spreaduniformly across the top of the moving bed in reactor vessel 10. For afuller disclosure of such a reactor vessel, reference is made tomy'copending application tiled -of even date herewith, now U.S. Patent2,838,381. Each leg 12 is'connected tothe bottom 'of vessel 10 through atruncated cone 11 (Figs. l and 2). Since the catalyst ow down througheach leg 12 may be individually controlled, anytdesired relativedistrib1 tion of owing catalyst among the several legs 12 can be readilymaintained. Generally, instrumental control is directed towardsmaintenance of equal catalyst throughput in all lift conduits 40; also,equality of input through In a reactor vessel 10 with a plurality oflegs 12, the ability to close on one or more legs 12 allows a highdegree of operational flexibility. Catalyst ow through any leg 12 iseasily stopped by moving its inlet line 36 up until nozzle 38 meetsflaring 42 of lift conduit 40 thereby closing the annular opening 44. Yf For the purposes of this invention, it is advisable to design the leftconduits 40 so that each will handle on the order of 5000 barrels Yperday of charge oil; for such service, eachV conduit 40' will beapproximately Y12 inches in diameter, preferably tapeiing'to adiameter'of about 18 inches at its upper end. Particularly with reactor vesselswhich are 20 feet or more in diameter, vit is well to limit the size ofthe lift conduits 40 so thateach will handle a catalyst flow ratecorresponding to an oil charging rate not in excess of about 10,000barrels per day.

eration of the foregoing disclosure without departing from the spirit orscope thereof, only such limitations should be imposed as are indicatedby the appended claim.

What is claimed is:

A tubular leg open at one end from which it is adapted to dependvertically from and communicatev withrthe bottom' of a reactor, incombination with av contact material uplift conduit extendingcerrtrallyin said-leg Vfrom near the'bottom thereof vtojsubstan'tiallybeyond .theopen i end of said leg with a length suicient forit to reachaV point near the top of said reactor when installed, said upliftconduit being fastened solely'by its lower end to the bottom end ofVsaid leg with its walls and said lower Y end spaced from the walls andbottom end of said leg, a fluid inlet disposed in saidrbottom end anddischarging into said lower end of said uplift conduit, said legand saiduplift conduit Vbeingcylindrical and forming 'an annular spacetherebetween, an annular ,boiler vdisposed in said annular space, saidboiler having a plurality ot'V 'vertical tubes supported in parallel byupper and lower spaced tube sheets, a frusta-conical bathe disposed insaid leg below said lower tube sheet to form therebe# tween an annularplenum chamber into which the fbottom ends of said vertical tubesdischarge, alluid inlet in' communication lwith the upper portion Yofsaid plenum chamber, said bottomV ends of said vertical tubes:projecting below said Ilower Vtube sheet and said fluid inlet in fcommunication with said upper portion of said yplenum chamber, said balebeing sloped toward said uplift conduit and having its inner peripherypositioned adjacent the lower end of said uplift conduit, and an inletfor supply-v ing a fluid to the space in said leg beneath said baille.

References Cited in the le of this patent UNITED STATES PATENTS12,461,104 Bates Feb. 8, 1949 2,477,502 Utterback et al. July 26, 19492,493,218 Bergstrom ..-A Jan. 3, v1950 2,542,887 Watson Feb. 20,19512,557,842 Ruthruff .Tune 19, 1951 2,625,467 Barker Ian. 13, 19532,642,346 Keith June 16, 1953 2,672,407 Leffer Mar. 16, 1954 2,690,056Bergstrom Sept. 28, 1954 2,723,180 Celani Nov. 8, 1955 2,727,810 Le'erDec. 20, 1955 2,756,193 Bergstrom July 24,` 1956 2,765,265V BourguetOct. 2, 1956 2,838,381 1958 Daniels t June .10,

